Cores for electrical induction apparatus



1957 c. G. DUENKE CORES FOR ELECTRICAL INDUCTION APPARATUS Filed Aug.28, 1953' QLARENcE G. DU'ENKE FIG. 5.

Unite States Patent CORES FOR ELECTRICAL INDUCTION APPARATUS Clarence G.Duenke, Webster Groves, Mo., assignor to Moloney Electric Company, St.Louis, Mo., a corporation of Delaware Application August 28, 1953,Serial No. 377,093 4 Claims. (Cl. 336210) This invention relatesgenerally to cores for electrical induction apparatus and morespecifically to a core of the type having a pair of yokes between whichlegs are extended which contact at the opposite ends thereof with saidyokes, the predominant object of the invention being to provide such acore with laminated legs, the laminations of each of which are capableof slipping slightly with respect to each other in order to avoid thenecessity for providing precisely prepared faces on the opposite ends ofthe legs for contact with face portions on the yokes, as was the caseheretofore where no slipping of the leg laminations was provided for.

Fig. 1 is a top, plan view of a core constructed in accordance with thisinvention.

Fig. 2 is a side elevation of the core shown in plan in Fig. 1.

Fig. 3 is a vertical section taken on line 3-3 of Fig. l, a part beingshown in elevation.

Fig. 4 is a top, plan view of a modified form of the invention.

Fig. 5 is a vertical section taken on line 55 of Fig. 4.

Fig. 6 is a fragmentary section taken on line 66 of Fig. 5.

In the drawing, wherein are shown for purposes of illustration, merely,two embodiments of the invention, A designates the core shown in Figs.1, 2 and 3. The core A comprises a pair of loops 1 and 2 which providethe core with yokes, said yokes being preferably formed from grainoriented steel, which is wound spirally to the required dimensions, andannealed and bonded, with face portions 3 ground fiat and plane. It isto be noted that there is no necessity to remove burrs caused bygrinding of the face portions 3 on the yokes 1 and 2, as the laminationsof the yokes are shorted only on one side, normal interlaminarresistance being maintained.

The core A includes also a plurality of legs 4 made up of grain orientedsteel laminations cut to the required size and annealed and stacked. Thelaminations of each leg may be held together by tape material 5, woundabout each leg, and the opposite ends of each leg contact, respectively,with face portions 3 of the yokes 1 and 2. The yokes and legs may beheld together to provide a unitary core unit by bands 6 which embracethe two yokes 1 and 2 at the legs 4 and and whose opposite end portionsare joined by suitable clips 7, said bands being drawn taut so as tomake good electrical contact between the opposite ends of the legs andthe face portions of the yokes.

When assembled as shown in Figs. 1, 2 and 3 with normal clampingpressure applied by bands 6, or other mechanical clamping means, a lowaverage value of air gap is obtained at the points where the oppositeends of the legs 4 contact with the prepared face portions 3 of theyokes 1 and 2. Also, laminations of the legs 4 are so held in place inthe leg structures that these laminations may slip relative to eachother slightly and hence the necessity for providing six faces at theopposite ends 2,804,600 Patented Aug. 27, 1957 of the legs which areexactly perpendicular and parallel with..respect to each other iseliminated, thus making assembly of the core practical from amanufacturing standpoint.

In Figs. 4, 5, and 6 a slightly different form of the invention isillustrated. According to this form of the invention a pair of loops 8and 8 are employed which provide the core B with yokes, these yokesbeing preferably formed from grain oriented steel which is woundspirally to the required dimensions and annealed and bonded, with faceportions 9 ground flat and plane. Here, also, it is not necessary toremove burrs caused by grinding the face portions 9 on the yokes 8 and8, as the laminations of the yokes are shorted only on one side withnormal interlaminar resistance being maintained. The core B of Figs. 4,5 and 6 includes a plurality of legs 10 made up of grain oriented steellaminations, cut to the required size and annealed and stacked, theopposite end faces of said legs being disposed in contact with groundface portions 9 of the yokes 8 and 8. The laminations of each of thelegs 10 are held together in a manner to allow for slight movement ofsaid laminations relative to each other by a rod and nut assembly 11,which is shown to good advantage in Fig. 5. The rod and nut assembly 11of each leg comprises a rod 12 which is screwthreaded at its oppositeends and extends through a tube 13 formed of fiber, or other goodelectrical insulating material, this tube being extended through anopening 14 formed transversely through each leg and which is ofconsiderable greater diameter than the tube 13 so as to provide anannular space 15 between the outer face of the tube and the wall of theopening 14. The rod of the rod and nut assembly of each leg has screwedon its opposite screwthreaded end portions, nuts 16 which engage againstthe outer faces of the outer laminations at opposite sides of the leg.

The loops 8 and 8' which provide the yokes of the core B are eachdisposed within a frame 17 which is of angular cross-section, as isshown to good advantage in Fig. 5, and at each leg of the core B aclamping structure 18 is provided. This clamping structure 18 comprisesa U-shaped member 19 having a bridge portion 19 at its bottom, andspaced legs 19 extending upwardly from the opposite ends of said bridgeportion, the yokes and legs of the core B being disposed between saidspaced legs with the lower leg of lower frame 17 contacting with thebridge portion 19 of the U-shaped member of the clamping structure 18.The spaced legs of the U-shaped member 19 of the clamping structure 18have formed therethrough adjacent to their upper ends apertures 20through which extensions 21 of a plate 22 project, said plate 22 beingextended transversely of the U-shaped member from the upper portion ofone spaced leg thereof to the upper portion of the opposite spaced legof said U-shaped member and being held in place by the projection of theextensions 21 of said plate 22 through the apertures 20 of the upperportions of the spaced legs of said U-shaped member. Also, a clampingscrew 23 is provided which extends screwthreadedly through an openingformed through the plate 22 and clampingly engages the horizontal, upperleg of the upper frame 17 so as to clamp the core B between saidclamping screw and the bridge portion 19* of the U-shaped member 19 ofthe clamping structure 18.

Thus, the laminations of the legs 10 of the core B are capable of slightslipping movement with respect to each other and hence the necessity forproviding faces at the opposite ends of said legs which are exactlyperpendicular and parallel with respect to each other is eliminated.

I claim:

1. A core for electrical induction apparatus comprising a plurality ofparallel legs, and laminated yokes at opposite ends of the legs, eachleg comprising a stack of laminations extending lengthwise of the leg,each leg having generally flat end faces, each yoke having portionswherein its laminations are generally coplanar with the laminations ofthe legs, said portions having flat inner faces in contact with the endfaces of the legs, only said flat inner faces of the yokes beingprepared to have the edges of the yoke laminations therein all flat andcoplanar and lying in a plane at right angles to the length of the legsand thereby being adapted for intimate contact with the ends of thelegs, insulating materialwound around each leg for holding itslaminations together while permitting endwise slippage of itslaminations relative to one another, and means for clamping the yokesagainst the end faces of the legs.

2. A core as set forth in claim 1 wherein said insulating materialcomprises tape wound spirally around the leg.

3. A core for electrical induction apparatus comprising a plurality ofparallel legs, and laminated yokes at opposite ends of the legs, eachleg comprising a stack of laminations extending lengthwise of the leg,each leg having generally flat end faces, each yoke having portionswherein its laminations are generally coplanar with the laminations ofthe legs, said portions having flat inner faces in contact with the endfaces of the legs, only said fiat inner faces of the yokes beingprepared to have the edges of the yoke laminations therein all flat andcoplanar and lying in a plane at right angles to the length of the legsand thereby being adapted for intimate contact with the ends of thelegs, each leg being provided with means for holding its laminationstogether while permitting endwise slippage of its laminations relativeto one another, said means holding said laminations of each legcomprising a fastener extending transversely through the leg, and meansfor clamping the yokes against the end faces of the legs.

4. A core for electrical induction apparatus comprising a plurality ofparallel legs, and laminated yokes at opposite ends of the legs, eachleg comprising a stack of laminations extending lengthwise of the leg,each leg having generally fiat end faces, each yoke having portionswherein its laminations are generally coplanar with the laminations ofthe legs, said portions having flat inner faces in contact with the endfaces of the legs, only said flat inner faces of the yokes beingprepared to have the edges of the yoke laminations therein all flat andcoplanar and lying in a plane at right angles to the length of the legsand thereby being adapted for intimate contact with the ends of thelegs, each leg being provided with means for holding its laminationstogether while permitting endwise slippage of its laminations relativeto one another, said means holding said laminations of each legcomprising a tube extending through an opening formed transverselythrough the leg, a fastener extending through the tube, said tube beingof smaller diameter than said opening, and means for clamping the yokesagainst the end faces of the legs.

References Cited in the file of this patent UNITED STATES PATENTS1,145,551 Burke July 6, 1915 1,406,246 Thordarson Feb. 14, 19221,834,898 Boyajian Dec. 1, 1931 2,522,244 Vienneau Sept. 12, 1950FOREIGN PATENTS 103,750 Switzerland Mar. 1, 1924 540,662 Great BritainOct. 24, 1941 637,142 Great Britain May 14, 1950 472,541 Italy June 23,1952 1,040,678 France Oct. 16, 1953

